使用Spring与多个数据源JNDI条目动态关联

Question

I have an existing simple Spring application with a DAO class that extends NamedParameterJdbcDaoSupport .

In the Spring context file, I have a "p:dataSource-ref" attribute that refers to a "jee:jndi-lookup" element, which references the JNDI name defined in the container.

Something like this:

<jee:jndi-lookup jndi-name="${jndiPrefix}/specificdb" id="mydb"/>
<bean class="com...dao.OrdersDAO" p:name="ordersDAO" p:dataSource-ref="mydb"/>

This all works fine. I've deployed this to both WebLogic and TomEE successfully.

I now need to consider a new application that has a slightly more dynamic relationship with its datasources. The overall dataflow of the new application will be very similar to the existing application.

The new application will have N datasources, all with the same data model. The container will have definitions for the JNDI names for all of the datasources, and I imagine I'll have to have an additional JNDI name that just contains a comma-separated string containing all of the JNDI names for the datasources.

What are some effective strategies for doing something like this in Spring?

Update :

One thing I didn't make clear in my original post is what kind of algorithm I would be using to "select" which datasource to use under the covers.

The point is, I'm not selecting a single datasource, I'm using all of them. The application requires the query to be run on all of the datasources and the resultset is the union of all of them.

The first answer describes a strategy that essentially connects a "facade" datasource to one of a set of other datasources. That's an interesting problem, but not what I'm looking for here.

In any case, I believe I understand how to do this, but I've yet to implement it yet. My intention is to dynamically create the set of datasources and associate them with a DAO (not sure whether I want a single DAO with a set of datasources or a 1-1 relationship between DAOs and datasources). An encompassing service will read a JNDI environment string at startup that contains a list of JNDI names for datasources, and dynamically create the DataSource objects. The query process will simply collect the results from each DataSource and union them together.

Answer 1

TomEE has the same kind of routing capabilities than Spring.

check these links out:

• http://tomee.apache.org/dynamic-datasource.html
• https://spring.io/blog/2007/01/23/dynamic-datasource-routing/